hesitation under heavy acceleration

S

Suny

Member
hey man, i just purchased Syclone #601. when i was talking to the previous owner, the owner took me for a ride and he was telling me some of the problems about the truck. the truck has a hesitation problem under heavy acceleration.

when i first start to put my foor into the accelerator the boost will go to about 10lbs. then boosts goes down to about 5 and seems to stay there. the truck hesitates and will get boost to about 10 lbs. i havent tried to keep accelerating under these conditions as i dont want to mess it up anymore, i checked the intake tube from the turbo to the intercooler. there some oil wetness on the tube to the intercooler, hte other thing is the hoseing from the intercooler to the intake dosent seem to the aligned properly. ill check the clamps for the hoseing and get the intercooler lined up with the intake first and try to drive it around and see what happens.

if anyone has had a problem with hesitation under load can you let me know as to what the problem was and what has been done to correct it?

thanks in advance suny
 
WyoSyclone

WyoSyclone

Active member
Re: hesitation under heavy acceleration

If it hasn't been done, first thing with these trucks is a good set of plugs (NGK UR5ix gapped at .030), wires, cap and rotor. Also, the vacuum lines (especially the hard plastic) tend to develop leaks - best to replace them and the check valves.

I'd do these two things first... then probably look at fuel issues (filter, pump, regulator).

Welcome to the wonderful world of SyTy's! :D
 
S

Suny

Member
Re: hesitation under heavy acceleration

Cool, ill be checking the ignition system this weekend and let you guys know whats happening with that. is there a diagram of all the Vacum lines and check valves here on the forum? ive gone threw several pages of tech stuff and havent found a thing. or maybe im just looking in all the wrong places.

im also wondering what the fuel pressure should be on a stock SyTy. i was told 35-45psi. and what is base timing supposed to be at? can someone guide me to a what to do guide after doing this quick tune up?
 
Last edited:
P

pinellas50

New Guy
Re: hesitation under heavy acceleration

Stock timing is zero with the tan/black wire unpluged. That wire is in the cab, under the carpet, up by the bottom of the dash on the pass side.

Is the truck down on power? I guess you might not know the answer to that having bought it this way.

And please describe hesitates.
 
S

Suny

Member
Re: hesitation under heavy acceleration

from a dead stop going WOT i can fell the power of the truck. then from ~3000 +/- 500 rpm, it bogs and has a hard time getting really good acceleration. it tends tend to kick and i get little bits of power from the truck. if i let off a bit and put my foot into it i can get the truck to work but it still bucks a little when accelerating. the other thing is if i put my foot into it slowly i can get decent acceleration threw out the whole range but it dosent feel as power full since its not running full boost or is at WOT.

it was suggested to check the ignition at first so im gonna check all that make sure the plugs are good as well as teh wires cap and rotor. there are some new screws in the cap but the cap looks old. i was alos asking some coworkers if they have a fuel pressure gauge i can borow. to see what the readin is at the fuel line. what is stock pressure supposed to be. 35-45psi? seesm a little low for a Turbo EFI considering the Vortecs run at 60psi.


pinellas50 said:
Stock timing is zero with the tan/black wire unpluged. That wire is in the cab, under the carpet, up by the bottom of the dash on the pass side.

Is the truck down on power? I guess you might not know the answer to that having bought it this way.

And please describe hesitates.
Click to expand...
 
turbodig

turbodig

Active member
Re: hesitation under heavy acceleration

Suny said:
it was suggested to check the ignition at first so im gonna check all that make sure the plugs are good as well as teh wires cap and rotor. there are some new screws in the cap but the cap looks old. i was alos asking some coworkers if they have a fuel pressure gauge i can borow. to see what the readin is at the fuel line. what is stock pressure supposed to be. 35-45psi? seesm a little low for a Turbo EFI considering the Vortecs run at 60psi.
Click to expand...

Could be ignition, I guess, but it sounds more like the overboost cutout if you still have the stock chip.

Stock fuel pressure was 38, no vacuum. At boost, pressure will be that + whatever boost you're running at.
 
turbodig

turbodig

Active member
Re: hesitation under heavy acceleration

One more thing... if it's been driven in this condition for very long, it could have very likely hurt something. Would be a good idea to do a compression check all the way around.
 
S

Suny

Member
Re: hesitation under heavy acceleration

I got a fuel pressure gauge on the truck today, drove it for a bit and as i suspected the pressure isnt keeping up with the RPMs and boost. it sits fine between 35-40psi. but as i slowly roll my foot into it it works great. i can even get decent accel with it. im hoping its just a plugged filter. cause sometimes it just bogs right down and the truck barelly accelerates. hoepfully the pump isnt the problem but if it is would putting a Walbro in it help it out?
 
Ry368

Ry368

one mile = 5280 feet
Re: hesitation under heavy acceleration

Damn....this sounds like the same problem i'm having with my rig as of yesterday. Been rolling around on 18-20 psi since i've owned it, but know it gets up to about 10 psi and starts lurching back and forth and throws no check engine light.....wierd!

My guess is fueling, but not sure.....and my hks pump for the electronic boost controller just keeps running so maybe a vac line going bad or the diaphram in the hks pump....phuckin trucks! :rant: :rotf: :lol:
 
S

sy445

New member
Re: hesitation under heavy acceleration

I just had similar prob and to my suprise something as simple as spark plugs was my cause. Never saw plugs with less than 200 miles that looked good foul that bad til I got this truck.
 
S

Suny

Member
Re: hesitation under heavy acceleration

sy445 said:
I just had similar prob and to my suprise something as simple as spark plugs was my cause. Never saw plugs with less than 200 miles that looked good foul that bad til I got this truck.
Click to expand...

hmmmmmm... im taking it to my friends shop soon anyways. they are getting a new snap on scanner tomorow. so im gonna have to chill with them for a bit and see what kinda data im getting.
 
S

Suny

Member
Re: hesitation under heavy acceleration

I statrted to get a CEL coming on so i took it to my friends shop, they just got a newscanner for their place and they said theyd check out my truck for free. turns out the vacume line to the MAP sensor was fuct. im looking at doing the rest of the hose replacement. does anyone have a diagram for the hoseing. or is their a thread about it already?

thanks in advance.
 
S

Suny

Member
Re: hesitation under heavy acceleration

I started to do a basic tuneup on my truck today and found a couple of problems that are probably the root of my problems. the Cruise control vac line isnt connected. i tried to find an open nipple or air line. i looked at the diagram on the rad cowl and it dosent show much. if someone can direct me to where there should be a T fitting or check valve thanks.

Also one of the screw holes for the distributor is stripped so only half of the distributor sits properly on the houseing. do i need to replace the whole thing or can i tap the threads and use a larger bolt?

Since winter is comeing im also thinking of pulling the engine and getting my friends at his shop to go over the engine. it seems like the previous owner got hosed on this engine. although he did get a couple of good things for it. eagle rods and diamond pistons.

the truck still dosent run properly but id like to switch the heads and cam and put a four bolt in it. then go from there.

but first the cruise hose and the distributor A's please and thanks.

if my truck is doing better after that then ill still be thinking of the rest of the running mods.


one last thing, their seems to be a little kink in my wastegate actuactor close to the actuator itself. the cylinder. i know this system is prone to bending rods and im wondering if this little kink may also be part of my problem.
 
Last edited:
J

jpalmer

New member
Re: hesitation under heavy acceleration

get it running right first , go silicone on the vac lines. if you start pulling stuff apart and modding and are still not running right, you could easily kill your motor you want to build. take it slow and dont drive it hard till you figure it out or you will kill somethin, i know this from personal exp. Good luck:tup:
 
You must log in or register to reply here.
Top